The 1% oxalic acid solution, an integral part of the Elastica by Miller staining kit, consists mainly of crystalline oxalic acid and aqua bidest. This solution is primarily used in medical, histological and scientific laboratories.

Oxalic acid, chemically known as ethanedioic acid, has the molecular formula C2H2O4 and consists of two carboxy groups (-COOH). It has a central role in tissue staining by acting as a fixative and bleaching agent, which is of great importance in the preparation of tissue sections.

During the staining process, oxalic acid specifically interacts with tissue components, especially elastic fibers. This reaction results in a color change of the treated tissues, which facilitates visible differentiation of tissue structures under the microscope. Essentially, oxalic acid supports the formation of stable color complexes that lead to differentiation and highlighting of elastic fibers in the histological specimen.